CVE-2026-107586

Allocation of Resources Without Limits or Throttling in hMailServer

Published Oct 8, 2026 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
Uncontrolled eviction in the browser session table of the REST API in Progressive Robot hMailServer 6.2.28 through 6.3.5 allows a remote authenticated user to end other users' sessions. The table of browser sessions, shared by every account, the server administrator and support sessions, dropped its least recently used session whenever it was full, whoever it belonged to, and placed no limit on how many sessions one account could hold. A user who repeatedly signs in with their own mailbox password can therefore keep the table full and sign out every webmail and administration session that is idle for more than a short time, for as long as they continue.

Remediation

Vendor Solution

Upgrade to hMailServer 6.3.6, in which each account or administrator holds at most fifty sessions and gives up its own least recently used one, and a full table makes room out of the sessions of whoever holds the most. Until then: limit the rate of POST /api/v1/session per client at a reverse proxy in front of the listener, and disable an account found signing in repeatedly (its sign-ins are in the application log and its device list).

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Progressive Robot
Progressive Robot hmailserver
Vendors & Products Progressive Robot
Progressive Robot hmailserver
Type Values Removed Values Added
Description Uncontrolled eviction in the browser session table of the REST API in Progressive Robot hMailServer 6.2.28 through 6.3.5 allows a remote authenticated user to end other users' sessions. The table of browser sessions, shared by every account, the server administrator and support sessions, dropped its least recently used session whenever it was full, whoever it belonged to, and placed no limit on how many sessions one account could hold. A user who repeatedly signs in with their own mailbox password can therefore keep the table full and sign out every webmail and administration session that is idle for more than a short time, for as long as they continue.
Title Allocation of Resources Without Limits or Throttling in hMailServer
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitLab
Published
Updated
Oct 8, 2026, 7:12 PM
Reserved
Oct 8, 2026, 10:52 AM
Status
Deferred
Published
Oct 8, 2026, 3:17 PM
Modified
Oct 8, 2026, 9:02 PM